Spectral Shifts of Semiconductor Clusters

The shifts of the electronic absorption spectra of GaAs and GaP semiconductor clusters are calculated using accurate pseudopotentials. In the absence of experimental data at present, these calculations provide estimates of expected spectral shifts in these clusters. In addition, these calculations show that Coulomb interaction between the electron and hole dominates over the confinement energy in small clusters, with the result that the electronic absorption spectra of small clusters exhibit redshift instead of blueshift as the cluster size is decreased.